1 files changed, 185 insertions, 81 deletions

diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
index fa2e49d432ff..a07866f1060c 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -13,6 +13,7 @@
 
 
 #include <linux/kernel.h>
+#include <linux/kstrtox.h>
 #include <linux/string.h>
 #include <linux/usb.h>
 #include <linux/usb/hcd.h>
@@ -35,7 +36,7 @@ static ssize_t field##_show(struct device *dev,				\
 		return -EINTR;						\
 	actconfig = udev->actconfig;					\
 	if (actconfig)							\
-		rc = sprintf(buf, format_string,			\
+		rc = sysfs_emit(buf, format_string,			\
 				actconfig->desc.field);			\
 	usb_unlock_device(udev);					\
 	return rc;							\
@@ -61,7 +62,7 @@ static ssize_t bMaxPower_show(struct device *dev,
 		return -EINTR;
 	actconfig = udev->actconfig;
 	if (actconfig)
-		rc = sprintf(buf, "%dmA\n", usb_get_max_power(udev, actconfig));
+		rc = sysfs_emit(buf, "%dmA\n", usb_get_max_power(udev, actconfig));
 	usb_unlock_device(udev);
 	return rc;
 }
@@ -80,7 +81,7 @@ static ssize_t configuration_show(struct device *dev,
 		return -EINTR;
 	actconfig = udev->actconfig;
 	if (actconfig && actconfig->string)
-		rc = sprintf(buf, "%s\n", actconfig->string);
+		rc = sysfs_emit(buf, "%s\n", actconfig->string);
 	usb_unlock_device(udev);
 	return rc;
 }
@@ -114,7 +115,7 @@ static ssize_t devspec_show(struct device *dev, struct device_attribute *attr,
 {
 	struct device_node *of_node = dev->of_node;
 
-	return sprintf(buf, "%pOF\n", of_node);
+	return sysfs_emit(buf, "%pOF\n", of_node);
 }
 static DEVICE_ATTR_RO(devspec);
 #endif
@@ -131,7 +132,7 @@ static ssize_t  name##_show(struct device *dev,				\
 	retval = usb_lock_device_interruptible(udev);			\
 	if (retval < 0)							\
 		return -EINTR;						\
-	retval = sprintf(buf, "%s\n", udev->name);			\
+	retval = sysfs_emit(buf, "%s\n", udev->name);			\
 	usb_unlock_device(udev);					\
 	return retval;							\
 }									\
@@ -160,9 +161,6 @@ static ssize_t speed_show(struct device *dev, struct device_attribute *attr,
 	case USB_SPEED_HIGH:
 		speed = "480";
 		break;
-	case USB_SPEED_WIRELESS:
-		speed = "480";
-		break;
 	case USB_SPEED_SUPER:
 		speed = "5000";
 		break;
@@ -175,7 +173,7 @@ static ssize_t speed_show(struct device *dev, struct device_attribute *attr,
 	default:
 		speed = "unknown";
 	}
-	return sprintf(buf, "%s\n", speed);
+	return sysfs_emit(buf, "%s\n", speed);
 }
 static DEVICE_ATTR_RO(speed);
 
@@ -185,7 +183,7 @@ static ssize_t rx_lanes_show(struct device *dev, struct device_attribute *attr,
 	struct usb_device *udev;
 
 	udev = to_usb_device(dev);
-	return sprintf(buf, "%d\n", udev->rx_lanes);
+	return sysfs_emit(buf, "%d\n", udev->rx_lanes);
 }
 static DEVICE_ATTR_RO(rx_lanes);
 
@@ -195,7 +193,7 @@ static ssize_t tx_lanes_show(struct device *dev, struct device_attribute *attr,
 	struct usb_device *udev;
 
 	udev = to_usb_device(dev);
-	return sprintf(buf, "%d\n", udev->tx_lanes);
+	return sysfs_emit(buf, "%d\n", udev->tx_lanes);
 }
 static DEVICE_ATTR_RO(tx_lanes);
 
@@ -205,7 +203,7 @@ static ssize_t busnum_show(struct device *dev, struct device_attribute *attr,
 	struct usb_device *udev;
 
 	udev = to_usb_device(dev);
-	return sprintf(buf, "%d\n", udev->bus->busnum);
+	return sysfs_emit(buf, "%d\n", udev->bus->busnum);
 }
 static DEVICE_ATTR_RO(busnum);
 
@@ -215,7 +213,7 @@ static ssize_t devnum_show(struct device *dev, struct device_attribute *attr,
 	struct usb_device *udev;
 
 	udev = to_usb_device(dev);
-	return sprintf(buf, "%d\n", udev->devnum);
+	return sysfs_emit(buf, "%d\n", udev->devnum);
 }
 static DEVICE_ATTR_RO(devnum);
 
@@ -225,7 +223,7 @@ static ssize_t devpath_show(struct device *dev, struct device_attribute *attr,
 	struct usb_device *udev;
 
 	udev = to_usb_device(dev);
-	return sprintf(buf, "%s\n", udev->devpath);
+	return sysfs_emit(buf, "%s\n", udev->devpath);
 }
 static DEVICE_ATTR_RO(devpath);
 
@@ -237,7 +235,7 @@ static ssize_t version_show(struct device *dev, struct device_attribute *attr,
 
 	udev = to_usb_device(dev);
 	bcdUSB = le16_to_cpu(udev->descriptor.bcdUSB);
-	return sprintf(buf, "%2x.%02x\n", bcdUSB >> 8, bcdUSB & 0xff);
+	return sysfs_emit(buf, "%2x.%02x\n", bcdUSB >> 8, bcdUSB & 0xff);
 }
 static DEVICE_ATTR_RO(version);
 
@@ -247,7 +245,7 @@ static ssize_t maxchild_show(struct device *dev, struct device_attribute *attr,
 	struct usb_device *udev;
 
 	udev = to_usb_device(dev);
-	return sprintf(buf, "%d\n", udev->maxchild);
+	return sysfs_emit(buf, "%d\n", udev->maxchild);
 }
 static DEVICE_ATTR_RO(maxchild);
 
@@ -257,7 +255,7 @@ static ssize_t quirks_show(struct device *dev, struct device_attribute *attr,
 	struct usb_device *udev;
 
 	udev = to_usb_device(dev);
-	return sprintf(buf, "0x%x\n", udev->quirks);
+	return sysfs_emit(buf, "0x%x\n", udev->quirks);
 }
 static DEVICE_ATTR_RO(quirks);
 
@@ -267,7 +265,7 @@ static ssize_t avoid_reset_quirk_show(struct device *dev,
 	struct usb_device *udev;
 
 	udev = to_usb_device(dev);
-	return sprintf(buf, "%d\n", !!(udev->quirks & USB_QUIRK_RESET));
+	return sysfs_emit(buf, "%d\n", !!(udev->quirks & USB_QUIRK_RESET));
 }
 
 static ssize_t avoid_reset_quirk_store(struct device *dev,
@@ -275,9 +273,10 @@ static ssize_t avoid_reset_quirk_store(struct device *dev,
 				      const char *buf, size_t count)
 {
 	struct usb_device	*udev = to_usb_device(dev);
-	int			val, rc;
+	bool			val;
+	int			rc;
 
-	if (sscanf(buf, "%d", &val) != 1 || val < 0 || val > 1)
+	if (kstrtobool(buf, &val) != 0)
 		return -EINVAL;
 	rc = usb_lock_device_interruptible(udev);
 	if (rc < 0)
@@ -297,7 +296,7 @@ static ssize_t urbnum_show(struct device *dev, struct device_attribute *attr,
 	struct usb_device *udev;
 
 	udev = to_usb_device(dev);
-	return sprintf(buf, "%d\n", atomic_read(&udev->urbnum));
+	return sysfs_emit(buf, "%d\n", atomic_read(&udev->urbnum));
 }
 static DEVICE_ATTR_RO(urbnum);
 
@@ -305,8 +304,8 @@ static ssize_t ltm_capable_show(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	if (usb_device_supports_ltm(to_usb_device(dev)))
-		return sprintf(buf, "%s\n", "yes");
-	return sprintf(buf, "%s\n", "no");
+		return sysfs_emit(buf, "%s\n", "yes");
+	return sysfs_emit(buf, "%s\n", "no");
 }
 static DEVICE_ATTR_RO(ltm_capable);
 
@@ -317,20 +316,21 @@ static ssize_t persist_show(struct device *dev, struct device_attribute *attr,
 {
 	struct usb_device *udev = to_usb_device(dev);
 
-	return sprintf(buf, "%d\n", udev->persist_enabled);
+	return sysfs_emit(buf, "%d\n", udev->persist_enabled);
 }
 
 static ssize_t persist_store(struct device *dev, struct device_attribute *attr,
 			     const char *buf, size_t count)
 {
 	struct usb_device *udev = to_usb_device(dev);
-	int value, rc;
+	bool value;
+	int rc;
 
 	/* Hubs are always enabled for USB_PERSIST */
 	if (udev->descriptor.bDeviceClass == USB_CLASS_HUB)
 		return -EPERM;
 
-	if (sscanf(buf, "%d", &value) != 1)
+	if (kstrtobool(buf, &value) != 0)
 		return -EINVAL;
 
 	rc = usb_lock_device_interruptible(udev);
@@ -372,7 +372,7 @@ static ssize_t connected_duration_show(struct device *dev,
 {
 	struct usb_device *udev = to_usb_device(dev);
 
-	return sprintf(buf, "%u\n",
+	return sysfs_emit(buf, "%u\n",
 			jiffies_to_msecs(jiffies - udev->connect_time));
 }
 static DEVICE_ATTR_RO(connected_duration);
@@ -394,14 +394,14 @@ static ssize_t active_duration_show(struct device *dev,
 		duration = jiffies_to_msecs(jiffies + udev->active_duration);
 	else
 		duration = jiffies_to_msecs(udev->active_duration);
-	return sprintf(buf, "%u\n", duration);
+	return sysfs_emit(buf, "%u\n", duration);
 }
 static DEVICE_ATTR_RO(active_duration);
 
 static ssize_t autosuspend_show(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
-	return sprintf(buf, "%d\n", dev->power.autosuspend_delay / 1000);
+	return sysfs_emit(buf, "%d\n", dev->power.autosuspend_delay / 1000);
 }
 
 static ssize_t autosuspend_store(struct device *dev,
@@ -442,7 +442,7 @@ static ssize_t level_show(struct device *dev, struct device_attribute *attr,
 	warn_level();
 	if (udev->state != USB_STATE_SUSPENDED && !udev->dev.power.runtime_auto)
 		p = on_string;
-	return sprintf(buf, "%s\n", p);
+	return sysfs_emit(buf, "%s\n", p);
 }
 
 static ssize_t level_store(struct device *dev, struct device_attribute *attr,
@@ -490,7 +490,7 @@ static ssize_t usb2_hardware_lpm_show(struct device *dev,
 	else
 		p = "disabled";
 
-	return sprintf(buf, "%s\n", p);
+	return sysfs_emit(buf, "%s\n", p);
 }
 
 static ssize_t usb2_hardware_lpm_store(struct device *dev,
@@ -505,7 +505,7 @@ static ssize_t usb2_hardware_lpm_store(struct device *dev,
 	if (ret < 0)
 		return -EINTR;
 
-	ret = strtobool(buf, &value);
+	ret = kstrtobool(buf, &value);
 
 	if (!ret) {
 		udev->usb2_hw_lpm_allowed = value;
@@ -529,7 +529,7 @@ static ssize_t usb2_lpm_l1_timeout_show(struct device *dev,
 					char *buf)
 {
 	struct usb_device *udev = to_usb_device(dev);
-	return sprintf(buf, "%d\n", udev->l1_params.timeout);
+	return sysfs_emit(buf, "%d\n", udev->l1_params.timeout);
 }
 
 static ssize_t usb2_lpm_l1_timeout_store(struct device *dev,
@@ -552,7 +552,7 @@ static ssize_t usb2_lpm_besl_show(struct device *dev,
 				  struct device_attribute *attr, char *buf)
 {
 	struct usb_device *udev = to_usb_device(dev);
-	return sprintf(buf, "%d\n", udev->l1_params.besl);
+	return sysfs_emit(buf, "%d\n", udev->l1_params.besl);
 }
 
 static ssize_t usb2_lpm_besl_store(struct device *dev,
@@ -589,7 +589,7 @@ static ssize_t usb3_hardware_lpm_u1_show(struct device *dev,
 
 	usb_unlock_device(udev);
 
-	return sprintf(buf, "%s\n", p);
+	return sysfs_emit(buf, "%s\n", p);
 }
 static DEVICE_ATTR_RO(usb3_hardware_lpm_u1);
 
@@ -611,7 +611,7 @@ static ssize_t usb3_hardware_lpm_u2_show(struct device *dev,
 
 	usb_unlock_device(udev);
 
-	return sprintf(buf, "%s\n", p);
+	return sysfs_emit(buf, "%s\n", p);
 }
 static DEVICE_ATTR_RO(usb3_hardware_lpm_u2);
 
@@ -670,6 +670,7 @@ static int add_power_attributes(struct device *dev)
 
 static void remove_power_attributes(struct device *dev)
 {
+	sysfs_unmerge_group(&dev->kobj, &usb3_hardware_lpm_attr_group);
 	sysfs_unmerge_group(&dev->kobj, &usb2_hardware_lpm_attr_group);
 	sysfs_unmerge_group(&dev->kobj, &power_attr_group);
 }
@@ -694,7 +695,7 @@ field##_show(struct device *dev, struct device_attribute *attr,	\
 	struct usb_device *udev;					\
 									\
 	udev = to_usb_device(dev);					\
-	return sprintf(buf, format_string, 				\
+	return sysfs_emit(buf, format_string,				\
 			le16_to_cpu(udev->descriptor.field));		\
 }									\
 static DEVICE_ATTR_RO(field)
@@ -711,7 +712,7 @@ field##_show(struct device *dev, struct device_attribute *attr,	\
 	struct usb_device *udev;					\
 									\
 	udev = to_usb_device(dev);					\
-	return sprintf(buf, format_string, udev->descriptor.field);	\
+	return sysfs_emit(buf, format_string, udev->descriptor.field);	\
 }									\
 static DEVICE_ATTR_RO(field)
 
@@ -727,7 +728,7 @@ static ssize_t authorized_show(struct device *dev,
 			       struct device_attribute *attr, char *buf)
 {
 	struct usb_device *usb_dev = to_usb_device(dev);
-	return snprintf(buf, PAGE_SIZE, "%u\n", usb_dev->authorized);
+	return sysfs_emit(buf, "%u\n", usb_dev->authorized);
 }
 
 /*
@@ -741,14 +742,14 @@ static ssize_t authorized_store(struct device *dev,
 {
 	ssize_t result;
 	struct usb_device *usb_dev = to_usb_device(dev);
-	unsigned val;
-	result = sscanf(buf, "%u\n", &val);
-	if (result != 1)
+	bool val;
+
+	if (kstrtobool(buf, &val) != 0)
 		result = -EINVAL;
-	else if (val == 0)
-		result = usb_deauthorize_device(usb_dev);
-	else
+	else if (val)
 		result = usb_authorize_device(usb_dev);
+	else
+		result = usb_deauthorize_device(usb_dev);
 	return result < 0 ? result : size;
 }
 static DEVICE_ATTR_IGNORE_LOCKDEP(authorized, S_IRUGO | S_IWUSR,
@@ -849,17 +850,11 @@ static const struct attribute_group dev_string_attr_grp = {
 	.is_visible =	dev_string_attrs_are_visible,
 };
 
-const struct attribute_group *usb_device_groups[] = {
-	&dev_attr_grp,
-	&dev_string_attr_grp,
-	NULL
-};
-
 /* Binary descriptors */
 
 static ssize_t
-read_descriptors(struct file *filp, struct kobject *kobj,
-		struct bin_attribute *attr,
+descriptors_read(struct file *filp, struct kobject *kobj,
+		const struct bin_attribute *attr,
 		char *buf, loff_t off, size_t count)
 {
 	struct device *dev = kobj_to_dev(kobj);
@@ -868,11 +863,7 @@ read_descriptors(struct file *filp, struct kobject *kobj,
 	size_t srclen, n;
 	int cfgno;
 	void *src;
-	int retval;
 
-	retval = usb_lock_device_interruptible(udev);
-	if (retval < 0)
-		return -EINTR;
 	/* The binary attribute begins with the device descriptor.
 	 * Following that are the raw descriptor entries for all the
 	 * configurations (config plus subsidiary descriptors).
@@ -884,7 +875,7 @@ read_descriptors(struct file *filp, struct kobject *kobj,
 			srclen = sizeof(struct usb_device_descriptor);
 		} else {
 			src = udev->rawdescriptors[cfgno];
-			srclen = __le16_to_cpu(udev->config[cfgno].desc.
+			srclen = le16_to_cpu(udev->config[cfgno].desc.
 					wTotalLength);
 		}
 		if (off < srclen) {
@@ -897,14 +888,71 @@ read_descriptors(struct file *filp, struct kobject *kobj,
 			off -= srclen;
 		}
 	}
-	usb_unlock_device(udev);
 	return count - nleft;
 }
+static const BIN_ATTR_RO(descriptors, 18 + 65535); /* dev descr + max-size raw descriptor */
+
+static ssize_t
+bos_descriptors_read(struct file *filp, struct kobject *kobj,
+		const struct bin_attribute *attr,
+		char *buf, loff_t off, size_t count)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct usb_device *udev = to_usb_device(dev);
+	struct usb_host_bos *bos = udev->bos;
+	struct usb_bos_descriptor *desc;
+	size_t desclen, n = 0;
+
+	if (bos) {
+		desc = bos->desc;
+		desclen = le16_to_cpu(desc->wTotalLength);
+		if (off < desclen) {
+			n = min(count, desclen - (size_t) off);
+			memcpy(buf, (void *) desc + off, n);
+		}
+	}
+	return n;
+}
+static const BIN_ATTR_RO(bos_descriptors, 65535); /* max-size BOS */
+
+/* When modifying this list, be sure to modify dev_bin_attrs_are_visible()
+ * accordingly.
+ */
+static const struct bin_attribute *const dev_bin_attrs[] = {
+	&bin_attr_descriptors,
+	&bin_attr_bos_descriptors,
+	NULL
+};
+
+static umode_t dev_bin_attrs_are_visible(struct kobject *kobj,
+		const struct bin_attribute *a, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct usb_device *udev = to_usb_device(dev);
+
+	/*
+	 * There's no need to check if the descriptors attribute should
+	 * be visible because all devices have a device descriptor. The
+	 * bos_descriptors attribute should be visible if and only if
+	 * the device has a BOS, so check if it exists here.
+	 */
+	if (a == &bin_attr_bos_descriptors) {
+		if (udev->bos == NULL)
+			return 0;
+	}
+	return a->attr.mode;
+}
 
-static struct bin_attribute dev_bin_attr_descriptors = {
-	.attr = {.name = "descriptors", .mode = 0444},
-	.read = read_descriptors,
-	.size = 18 + 65535,	/* dev descr + max-size raw descriptor */
+static const struct attribute_group dev_bin_attr_grp = {
+	.bin_attrs =	dev_bin_attrs,
+	.is_bin_visible =	dev_bin_attrs_are_visible,
+};
+
+const struct attribute_group *usb_device_groups[] = {
+	&dev_attr_grp,
+	&dev_string_attr_grp,
+	&dev_bin_attr_grp,
+	NULL
 };
 
 /*
@@ -918,7 +966,7 @@ static ssize_t authorized_default_show(struct device *dev,
 	struct usb_hcd *hcd;
 
 	hcd = bus_to_hcd(usb_bus);
-	return snprintf(buf, PAGE_SIZE, "%u\n", hcd->dev_policy);
+	return sysfs_emit(buf, "%u\n", hcd->dev_policy);
 }
 
 static ssize_t authorized_default_store(struct device *dev,
@@ -957,7 +1005,7 @@ static ssize_t interface_authorized_default_show(struct device *dev,
 	struct usb_device *usb_dev = to_usb_device(dev);
 	struct usb_hcd *hcd = bus_to_hcd(usb_dev->bus);
 
-	return sprintf(buf, "%u\n", !!HCD_INTF_AUTHORIZED(hcd));
+	return sysfs_emit(buf, "%u\n", !!HCD_INTF_AUTHORIZED(hcd));
 }
 
 /*
@@ -975,7 +1023,7 @@ static ssize_t interface_authorized_default_store(struct device *dev,
 	int rc = count;
 	bool val;
 
-	if (strtobool(buf, &val) != 0)
+	if (kstrtobool(buf, &val) != 0)
 		return -EINVAL;
 
 	if (val)
@@ -1022,10 +1070,6 @@ int usb_create_sysfs_dev_files(struct usb_device *udev)
 	struct device *dev = &udev->dev;
 	int retval;
 
-	retval = device_create_bin_file(dev, &dev_bin_attr_descriptors);
-	if (retval)
-		goto error;
-
 	retval = add_persist_attributes(dev);
 	if (retval)
 		goto error;
@@ -1055,7 +1099,6 @@ void usb_remove_sysfs_dev_files(struct usb_device *udev)
 
 	remove_power_attributes(dev);
 	remove_persist_attributes(dev);
-	device_remove_bin_file(dev, &dev_bin_attr_descriptors);
 }
 
 /* Interface Association Descriptor fields */
@@ -1066,7 +1109,7 @@ iad_##field##_show(struct device *dev, struct device_attribute *attr,	\
 {									\
 	struct usb_interface *intf = to_usb_interface(dev);		\
 									\
-	return sprintf(buf, format_string,				\
+	return sysfs_emit(buf, format_string,				\
 			intf->intf_assoc->field); 			\
 }									\
 static DEVICE_ATTR_RO(iad_##field)
@@ -1085,7 +1128,7 @@ field##_show(struct device *dev, struct device_attribute *attr,		\
 {									\
 	struct usb_interface *intf = to_usb_interface(dev);		\
 									\
-	return sprintf(buf, format_string,				\
+	return sysfs_emit(buf, format_string,				\
 			intf->cur_altsetting->desc.field); 		\
 }									\
 static DEVICE_ATTR_RO(field)
@@ -1107,7 +1150,7 @@ static ssize_t interface_show(struct device *dev, struct device_attribute *attr,
 	string = READ_ONCE(intf->cur_altsetting->string);
 	if (!string)
 		return 0;
-	return sprintf(buf, "%s\n", string);
+	return sysfs_emit(buf, "%s\n", string);
 }
 static DEVICE_ATTR_RO(interface);
 
@@ -1122,7 +1165,8 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
 	udev = interface_to_usbdev(intf);
 	alt = READ_ONCE(intf->cur_altsetting);
 
-	return sprintf(buf, "usb:v%04Xp%04Xd%04Xdc%02Xdsc%02Xdp%02X"
+	return sysfs_emit(buf,
+			"usb:v%04Xp%04Xd%04Xdc%02Xdsc%02Xdp%02X"
 			"ic%02Xisc%02Xip%02Xin%02X\n",
 			le16_to_cpu(udev->descriptor.idVendor),
 			le16_to_cpu(udev->descriptor.idProduct),
@@ -1150,7 +1194,7 @@ static ssize_t supports_autosuspend_show(struct device *dev,
 	s = (!dev->driver || to_usb_driver(dev->driver)->supports_autosuspend);
 	device_unlock(dev);
 
-	return sprintf(buf, "%u\n", s);
+	return sysfs_emit(buf, "%u\n", s);
 }
 static DEVICE_ATTR_RO(supports_autosuspend);
 
@@ -1163,7 +1207,7 @@ static ssize_t interface_authorized_show(struct device *dev,
 {
 	struct usb_interface *intf = to_usb_interface(dev);
 
-	return sprintf(buf, "%u\n", intf->authorized);
+	return sysfs_emit(buf, "%u\n", intf->authorized);
 }
 
 /*
@@ -1174,14 +1218,24 @@ static ssize_t interface_authorized_store(struct device *dev,
 {
 	struct usb_interface *intf = to_usb_interface(dev);
 	bool val;
+	struct kernfs_node *kn;
 
-	if (strtobool(buf, &val) != 0)
+	if (kstrtobool(buf, &val) != 0)
 		return -EINVAL;
 
-	if (val)
+	if (val) {
 		usb_authorize_interface(intf);
-	else
-		usb_deauthorize_interface(intf);
+	} else {
+		/*
+		 * Prevent deadlock if another process is concurrently
+		 * trying to unregister intf.
+		 */
+		kn = sysfs_break_active_protection(&dev->kobj, &attr->attr);
+		if (kn) {
+			usb_deauthorize_interface(intf);
+			sysfs_unbreak_active_protection(kn);
+		}
+	}
 
 	return count;
 }
@@ -1230,9 +1284,59 @@ static const struct attribute_group intf_assoc_attr_grp = {
 	.is_visible =	intf_assoc_attrs_are_visible,
 };
 
+static ssize_t wireless_status_show(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	struct usb_interface *intf;
+
+	intf = to_usb_interface(dev);
+	if (intf->wireless_status == USB_WIRELESS_STATUS_DISCONNECTED)
+		return sysfs_emit(buf, "%s\n", "disconnected");
+	return sysfs_emit(buf, "%s\n", "connected");
+}
+static DEVICE_ATTR_RO(wireless_status);
+
+static struct attribute *intf_wireless_status_attrs[] = {
+	&dev_attr_wireless_status.attr,
+	NULL
+};
+
+static umode_t intf_wireless_status_attr_is_visible(struct kobject *kobj,
+		struct attribute *a, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct usb_interface *intf = to_usb_interface(dev);
+
+	if (a != &dev_attr_wireless_status.attr ||
+	    intf->wireless_status != USB_WIRELESS_STATUS_NA)
+		return a->mode;
+	return 0;
+}
+
+static const struct attribute_group intf_wireless_status_attr_grp = {
+	.attrs =	intf_wireless_status_attrs,
+	.is_visible =	intf_wireless_status_attr_is_visible,
+};
+
+int usb_update_wireless_status_attr(struct usb_interface *intf)
+{
+	struct device *dev = &intf->dev;
+	int ret;
+
+	ret = sysfs_update_group(&dev->kobj, &intf_wireless_status_attr_grp);
+	if (ret < 0)
+		return ret;
+
+	sysfs_notify(&dev->kobj, NULL, "wireless_status");
+	kobject_uevent(&dev->kobj, KOBJ_CHANGE);
+
+	return 0;
+}
+
 const struct attribute_group *usb_interface_groups[] = {
 	&intf_attr_grp,
 	&intf_assoc_attr_grp,
+	&intf_wireless_status_attr_grp,
 	NULL
 };